The technology of diving has improved dramatically since the days when divers walked the floor of the ocean with lead boots and a thick hose attached to a surface vessel. Today, the technology of choice for most divers, recreational and professional, is SCUBA (Self Contained Underwater Breathing Apparatus). While this technology has given divers increased mobility and more overall freedom, it has brought with it at least one significant problem; limited air supply.
While SCUBA divers are taught to scrupulously monitor their air usage and to surface immediately at the first sign of trouble this is often not enough. For example, if a diver becomes entangled in vegetation he may not be able to surface when his air supply is running out. This is compounded when the diver is far below surface and a decompression period is necessary to avoid potential decompression sickness (the bends) or an air embolism.
Efforts to avoid such out of air situations has led to the development of so-called secondary or redundant air supplies. These expensive devices provide a diver with a limited back-up supply of air sufficient to provide a number of extra breaths depending upon the depth. This is generally enough air to allow a diver to get to the surface from that depth using emergency ascendancy techniques (i.e., risk the bends, but don't drown). However, if a diver is entrapped, or otherwise incapacitated, an extra air supply is of limited value.
The only way to cope with entrapment or incapacitation situations is to secure assistance from another diver. That is why standard SCUBA diving procedure calls for every diver to have a "buddy." It is the buddy's job to keep track of his partner, to extricate him from entrapment, to share air with his partner if the partner runs out and to seek help if he is unable to provide sufficient assistance to his partner. Unfortunately, the buddy system is not perfect. In 1992, the Divers Alert Network ("DAN") reported that 17 percent of the divers in its database had an air problem, with 87 percent of those divers experiencing Type II Decompression Sickness, a mild form of the bends. DAN also reported that 96 divers died in 1992, 62 by drowning, with 34 of those due to out of air conditions.
The buddy system is imperfect for a number of reasons. First, if the buddy must go to the surface to seek help, he must surface slowly, spending time to decompress or he could be in trouble as well. Moreover, once the buddy has reached the surface, he can easily lose track of the down diver geographically, especially if a diving boat or platform is some distance from the point at which he surfaces. Still further, if the two divers are alone, the diver who has gone to the surface is usually not in a position to descend again to rescue the down diver. If the diving is being done in water with low visibility, it is very easy to lose a buddy. In such situations there is no way for the buddy to know his partner is in trouble until he has surfaced and his partner does not. At that point, the buddy will generally be unable to locate the down diver. Even if he can locate him, it will likely be too late.
Moreover, if a diver is in a distressed position and a buddy is attempting to assist him, there is no way for the rescuer to alert others of the situation. If a diver is in an out of air position and a buddy is attempting a rescue, it is standard procedure to raise the victim to the surface and drag him to safety (e.g., shore or a boat) so CPR can be performed. This is an extremely critical time for the victim. It can take as little as five minutes without air for permanent brain damage to occur. Every additional minute can make the difference between life and death. If a rescuer could notify the surface the instant he becomes aware of a problem, many lives could be saved.
A number of devices have been proposed which could conceivably be used to assist in the above-described situations. For example, U.S. Pat. No. 3,105,459 discloses a device which comprises a buoyant body having an integrated collapsible flagstaff. The body, which is unwieldy because of its inherently buoyant nature, is attached to the diver's gear and is supposed to be released when the diver is ready to ascend. The avowed purpose of the device is to warn those on the surface that a diver is surfacing to avoid having a boat run the diver down.
The use of buoyant flags to indicate the presence of divers is a common practice. In fact, in some states, such as Rhode Island, this practice is prescribed by a law which mandates that boats keep from getting within a set distance of such a flag and that divers actually tow the flag with them. Thus, the use of such flags will not indicate that a diver is in trouble below the surface--in fact, quite the contrary. Since there is no universal diver distress flag or codes, even the employment of a uniquely patterned flag will be ineffective. Moreover, the use of a non-luminescent, solely visual signal does no good if a potential rescuer is not looking directly at it or for it or if the incident occurs at night.
U.S. Pat. No. 3,760,440 discloses a device which is designed to permit a diver to communicate with the surface by the use of different colored air bags. Deflated air bags are carried down by a diver in a capsule which has a mouthpiece to enable the diver to inflate selected colored air bags. This device is not designed to identify a diver in trouble and provides only a non-luminescent, visual signal. Moreover, it requires that the diver use his own air supply to inflate the air bag. This would be unacceptable in a panic situation and impossible in an out of air situation.
U.S. Pat. No. 3,798,629 discloses an alarm system for divers which is designed to automatically operate when a diver's breathing cycle is compromised. The alarm device consists of an electronic circuit to detect a diver's breathing cycle coupled to a releasable alarm unit comprising a "sparkler" to inflate an attached balloon and an optional depth indicator and/or dye ampule. The alarm can be manually released.
This device requires complicated circuitry and a direct connection to a divers breathing apparatus. For much of its operation, it relies on springs and strings--components which are too unreliable in an emergency device designed to function in salt water. It also must be securely attached to a diver's body such that it can interact with a diver's breathing apparatus and may be unreachable in an entrapment situation. Further, the balloon is a non-luminescent, non-standard, visual signal which would not be seen at night, in choppy seas or in fog as it does not include any audible or luminescent signal capability. Even if seen, it would not be recognized at the surface as a distress signal by the uninformed.